Vapor recovery unit



June 6, 1951 N. N. SKAREDOFF VAPOR RECOVERY UNIT Filed Feb. l, 1960 l lll INVENTOR.' NlKoLAl N. sKAREDoFF B maf United States Patent 2,986,893 VAPOR RECGVERY UNIT Nikolai N. Skaredol, Port Washington, N .Y., assignor to Devenco Incorporated, New York, N.Y., a corporation of New York Filed Feb. 1, 1960, Ser. No. 5,923 2 Claims. (Cl. 62-54) r[his invention relates to apparatus for recovering vapors yielded by volatile liquids such as gasolines, and relates more particularly, to improved apparatus 4for condensing and thereby salvaging such vapors from vaporladen air.

Large losses are suiered annually by the evaporation of gasoline from storage tanks. Such evaporative loss occurs for example, during breathing that takes place as a result of moment-to-moment changes in atmospheric temperature and pressure. The vapor pressure of highly volatile liquid increases rapidly with temperature rise. Ordinarily, storage tanks are not designed to withstand internal pressure conditions that are greater or less than the outside pressure of the atmosphere, and therefore a continuous venting takes place whereby every rise in atmospheric temperature expels a quantity of air saturated with the valuable vapor and with every drop in temperature, a quantity of outside air is admitted to the tank only to be saturated with the vapor and subsequently to be expelled again on the occasion of the next temperature rise.

Similar losses occur when a tank is being iilled with a volatile product. The space above the liquid level becomes saturated with vapor and as the level rises there is an expulsion of vapor-laden air to the atmosphere.

It is a general object of this invention to provide a new and improved apparatus, which is both compact and economical, for salvaging valuable vapors from vapor-laden air which Iwould otherwise `be exhausted to the atmosphere and the vapors dissipated and lost. Toward this end, apparatus is provided comprising a seriesl of concentric cylinders, one of which is surrounded by a chilling coil of a refrigerating apparatus. The cylinders form a series of concentric passes through which the vapor-laden air Hows, and the passes are so arranged that the air guided therethrough is rst pre-cooled, then chilled to condense the vapors. The condensate is collected in a reservoir at the bottom of the unit, and the vapor-free air is exhausted through a stack to the atmosphere.

The concentiic arrangement of the passes produces a vapor recovery unit which offers maximum thermal eicie'ncy, together with unusual compactuess. Because of the compactness of the apparatus it can be manufactured and installed at low cost, and it is particularly suitable for installation on the roof of a storage tank containing a volatile liquid.

Another object of the invention is to provide a unit of the type described wherein the stack is provided with a rotary exhaust head in order that an adequate draft is produced at all times.

Other objects of the present invention will be apparent from the following description.

In the drawings:

FIG. 1 is a vert-ical view of the apparatus, the left half of which is a cross-sectional view taken on line 1-1 of FIG. "2, and the right half of which shows portions of the three outermost cylinders broken away so that the exterior appearance of all the cylinders may be observed; and

FIG. 2 is a horizontal cross-sectional view taken on line 2-2 of FIG. 1.

Referring now to the drawings, a fuel vapor recovery unit designated generally by the reference numeral is shown supported on the roof of a storage tank 11 by ice means of the adjustable legs 12. The unit is provided with a cylindrical common housing 13 which comprises an outer jacket 14, an outer shell 15, and insulation material 1'6 therebetween. The housing has a similarly insulated bottom Wall comprising an outer plate 17 forming part of the outer jacket 14, an inner plate 52 forming part of the outer shell 15, and insulation material 51 therebetween, and a top wall comprising an inner plate 18 forming part of the outer shell 1'5, an outer plate 50 forming part of the outer jacket 14, and insulation material 53 therebetween. Supported on the outer plate 50 of the top wall is a weather hood 19 which is provided with a stack 20 preferably concentric therewith. Near the top of the common housing 13 there is located an inlet 21 which communicates with a pressure relief valve (not shown), the latter being connected to an outlet from the tank 11. The bottom of the housing 13 forms a liquid tray or reservoir 9 which holds the condensed vapors deposited by the air which ilows through the unit. Just above the reservoir 9 is a liquid outlet valve 22 which controls the ow of the liquid 23 from the reservoir 9 back into the storage tank 11. As may be seen clearly in the drawings,

therefore, the common housing 13 is completely enclosed except for the inlet 21, the outlet valve 22, and a central stack 24 which communicates with the stack 20 in the weather hood 19.

A short distance above the valve 22 the common housing 13 is provided with a liquid tray baie 25 having a diameter equal to the diameter of the outer shell 15. The baie is sloped downwardly toward its center at which point there is formed a drain 26 through which the condensed vapor which collects on the baille 25 tiows into the reservoir 9.

A second cylinder or shell 27 is suspended concentrically with the common housing 13 from the inner plate 18 of the top wall of the latter. The shell 27 is fabricated from heat-conducting material, and is spaced from the outer shell 15 in order to provide a passageway for air entering the unit 10 through the inlet 21. The shell 27 is also provided with an annular bottom wall 28 which is spaced above the baille 25 in order to provide a further passageway for the air which ows between the shell 27 and the outer shell 15. The bottom wall 28 is sloped inwardly and downwardly toward a pair (or more) of drains 29 through which the vapor which condenses on the bottom wall 28 may flow into the reservoir 9. The central hole 30 in the bottom wall 28 permits the air owing between the bottom wall 28 and the bafe 25 to continue its ow.

A third cylinder 31 is suspended from the inner plate 18 of the top wall of the common housing 13 concentric with the second shell 2'7. The cylinder comprises inner and outer shells 44 and 45 respectively, having insulation material 46 therebetween. The cylinder 31 is spaced from the shell 27 in order to form another pass for the air flowing through the unit 10. The cylinder 31 is provided with a top wall comprising an outer plate 32 forming part of the outer shell 45, an inner plate 54 forming part of the inner shell 44, an insulation material 5S therebetween. The inner plate 54 acts as a bale for the air owing into the cylinder through the hole 30 in the bottom wall 28. The plate 32 of the cylinder 31 is spaced from the plate 18 of the common housing 13 and above the outer plate 32 the outer shell 45 of the cylinder 31 is provided with a series of openings 33. These openings permit the air flowing through the space between the cylinder 31 and the cylinder 27 to flow into the space between the outer plate 32 of the cylinder 3-1 and the inner plate 118 of the common housing and from there into the stack 24.

A fourth or innermost cylinder 34 is suspended from the inner plate 54 of the cylinder 31 concentric'therewith. This cylinder is fabricated from heat-conductingv material. The side walls of the cylinder 34 are spaced from the side walls of the cylinder 31 in order to forni still another passageway for air flowing through the apparatus. Near the upper end of the` cylinder 34 the latter is provided with a series of openings 47 in order to permit air which ows through the central opening 30 and into the cylinder 34 to flow out of the cylinder 34 and into the space between the cylinder 34 and the cylinder 31.

A refrigerating apparatus is provided comprising a sealed motor-compressor unit 35 located within the weather hood 19, a chilling coil 36 which surrounds the fourth cylinder 34, and a condenser 37 located in the stack surrounding the stack 24. A control box 38 for controlling the operation of the motor-compressor unit 35 is also located within the weather hood 19.

Supported on the upper 4end of the stack 20 is a rotary exhaust head 39 which is provided with a vane 40. The rotary head 39 rotates with respect to the stack 2'0 as the direction of the wind changes, so that the opening 41 of the exhaust head always faces opposite to the drection from which the Wind is blowing. In this way, the maximum possible draft which the stack can create is always available. Around the periphery of the weather hood 19, at its lower end, are a series of cooling air inlet ports 42 through which atmospheric air is inducted. Just above the ports 42 the weather hood is provided with a lower Wall 43 which is spaced from the outer plate 50 of the top wall of the cornmon'housing 13. This spacing provides a passageway through which the atmospheric air inducted through thelports 42 may flow into the stack 26 and thus help to cool the condenser 37. As may be seen clearly in FIG. l the bottom wall 43 and the stack 20 are preferably formedV as an integral unit, in order to smoothly guide air from the ports 42 into the stack 20.

The manner in which vapor-laden air ows through the present unit and is thereby cooled in order to condense out the vapor which it carries may be seen by following the arrows in FIG. l. The vapor-laden air enters the unit through the inlet 21, from the outlet of a pressure relief valve (not shown). It then flows downwardly between the outer shell 1S and the second shell 27 until its direction is reversed by the liquid tray baffle whereupon it llows upwardly into the hole 3i] in the bottom wall 28 of the shell 27 and through the fourth cylinder 34. During this upward flow the air is preliminarily cooled by the chilling coil 36 of the refrigerating apparatus, since the cylinder 34 is heat-conducting, and some of the heat of the air is conducted through the cylinder to the chilling coil 36. The direction ot ow of the air is once again reversed by the inner plate 54 of the top wall of the third cylinder 31 and the air flows downwardly between the innermost cylinder 34 and the third cylinder 31 whereupon it is given its final cooling by the chilling coil 36. The direction of ow of the air is again changed, and most of the condensate deposited, when the air impinges on the bottom wall 2'8 of the second shell 27. This directs the dry chilled air upwardly between the third cylinder 31 and the second shell 27. Since the second shell 27 is of heat-conducting material, the cooled air owing between that shell and the third cylinder 31 tends to pre-cool the incoming air owing downwardly between the shell 27 and the outer shell 15. Thus, it may be seen that the two passes located between the outer shell 15 and the third cylin der 31 comprise an economizer chamber, insulated from the atmosphere by the common housing 13. Furthermore, the two passes located within the third cylinder 31 constitute a cooling chamber, insulated from the economizer chamber by the'cylinder 31.

, It' should be noted that the air travels through the 'I flow is mostly downward while the air is being cooled and upward while being. heated.

The reheated vapor-free air leaves the economizer chamber through the openings 33 in the outer shell 45 of the cylinder 31 and from there flows into the stack 24 formed by the inner wall of the condenser 37, then through the stack 20, and finally out the opening 41 in the exhaust head 39. In this way, the comparatively cool vapor-free exhaust air helps to cool the condenser 37, together with the atmospheric air inducted through the openings 42 in the weather hood 19.

The vapor which condenses out of the air during its downward flow through the economizer chamber and during its upward ow through the cooling chamber is deposited on the bale 25 and eventually flows out the drain 26 into the reservoir 9 at the bottom of the Ycommon housing 13. The vapor which is condensed out of the air during its downward flow through the chilling chamber and its upward ow through the economizer chamberv is deposited on the bottom wall 28 of the second shell 27 and tlows out the drains 29 into the reservoir 9. There is always a minimum liquid level in the reservoir and the lower ends of the drains 26 and 29 are disposed below this level so that the liquid serves to seal the ends of the drains. When it is desired to transfer the condensed vapors which have accumulated at the bottom of the common housing 13 to the storage tank 11 the valve 22 is actuated and the liquid ows by gravity back into the tank. Note that the valve 22 is arranged above the bot# tom of the common housing 13 in order that the minimum liquid level just mentioned is always maintained.

It will thus be understood that many of the details herein described and illustrated may be modied by those skilled in the art without necessarily departing from the spirit and scope of the invention as expressed in the appended claims. Except as otherwise stated, therefore, it is intended that these details be interpreted as illustrative only.

What is claimed is:

l. A fuel vapor recovery unit comprising four concent-ric spaced cylinders which are alternately heat-conducting and non-heat-conducting, the outermost cylinder forming an insulated housing for the unit, said housing having an inlet for vapor-laden air and an outlet for devaporized air, a cylindrically arranged chilling coil concentric with and adjacent to the innermost cylinder, a refrigerating apparatus for supplying a refrigerant to said coil, said concentric cylinders forming four concentric passes and serving to guide incoming air through the outermost pass, then through the innermost pass, .then through the pass adjacent the innermost pass, and finally through the pass adjacent the outermost pass to, said outlet, ya collecting reservoir in the lower end of said outermost cylinder for recovering fuel condensed during said flow, a stack connected to said outlet, and a rotary exhaust head upon said stack.

2. A fuel vapor recovery unit comprisingacentrally located hollow heat-conducting cylinder, a cylindrically arranged cooling coil concentric with and closely adja cent to said cylinder, a refrigeratingapparatus for supplying a refrigerant to said coil, an insulated cylinder concentric with and surrounding said heat-conducting cylinder, a second heat-conducting cylinder concentric with and surrounding said insulating cylinder, an outer cylindrical insulated housing concentric with and surrounding said second heat-conducting cylinder, said housing having'an inlet for vapor-laden air and an outlet for devaporized air, guiding walls formed in said housing in addition to the side walls of said cylinders for guiding incoming air downwardly between said housing and said second heat-conducting cylinder, then upwardly along the axis of said central heat-conducting cylinder in order to-cool theY air by means of said chilling coil, then downwardly between said central cylinder and saidnsulatingvcylinder sothat the air isurthercooled .by said -chillingcoh thnupwardf.

6 ly between said insulating cylinder and said second heat- References Cited in the file of this patent conducting cylinder in order to pre-cool the incoming air, and inally to said outlet, `and a collection reservoir in UNITED STATES PATENTS the lower end of said housing for accumulating the con- '830,613 Pictet Sept, 11, 1905 densation produced during the flow of air through the 5 1,083,983 Claude 1an, 13, 1914 unit, said refrgerating apparatus including a condenser 1,659,230 Cunningham May 8, 1928 located within said stack, said stack being provided at 2,004,074 Kiley june 4, 1935 its lower end with an inlet port for atmospheric air. 

